This invention relates to an apparatus for optically measuring the fat content of milk and associated products.
The customary process of measuring the fat content of milk and associated products comprises the steps of dissolving the protein contained in milk, for example, in a solution of caustic soda to produce fat particles in a thermostat maintained at a prescribed temperature; unifying the fat particles generally having widely varying sizes under pressure in a homogenizer, followed by uniform dispersion; applying visible beams of light to the dispersed fat particles; and finally detecting beams of light permeating the fat particles and also those scattered thereby so as to determine the fat content of milk.
Where milk makers use the above-mentioned type of milk fat content-measuring apparatus at the site, it is necessary to examine periodically as well as quickly whether a value indicated by said measuring apparatus agrees with a prescribed milk fat content. However, where said measuring apparatus is used particularly for a long period, a source of light for projecting light on fat particles and a detector for detecting permeating beams of light often indicate deterioration of property with time or due to variations in the environmental conditions, for example, ambient temperature, thus giving rise to errors of measurement. To date, therefore, the Gerber or Babcock method has been adopted for correction of such errors of measurement. To this end, another method has also been developed which consists in supplying a measuring apparatus with the solution of a specific chemical in place of milk which is considered to give the same optical result as milk fat. However, a measuring apparatus based on the Gerber or Babcock method which require sulfuric acid should be handled with care and moreover takes a longer time than 30 minutes in correcting the results of measurement. Therefore, other persons than well-skilled operators can not properly adjust the operation of the measuring apparatus. Further, where the conventional milk fat-measuring apparatus is used, it is necessary to provide a correction device based on the Gerber or Babcock method nearby. On the other hand, the correction method of charging the solution of a chemical into the measuring apparatus in place of milk is likely to give rise to differences between the actual fat content and the prescribed value of the solution of a chemical, depending on the process of preparing said solution and the changes with time suffered by the solution, failing to attain the accurate correction of the milk fat content-measuring apparatus.